The inductance of an inductor, a key component in electrical circuits, depends on several physical parameters and factors. The primary physical parameters that influence inductance are:

1. Number of Turns (N): The number of turns of wire in the coil of an inductor plays a crucial role in determining its inductance. More turns generally lead to higher inductance, as the magnetic field produced by each turn of wire contributes to the total inductance.

2. Cross-Sectional Area (A): The cross-sectional area of the coil also affects inductance. A larger cross-sectional area tends to increase inductance because it allows for a greater magnetic field to develop for a given current.

3. Length of the Coil (l): The physical length of the coil or the length of the wire wound around the core affects inductance. A longer coil typically results in higher inductance, as it provides more space for the magnetic field to develop.

4. Permeability of the Core Material (μ): If an inductor has a magnetic core, the permeability of that core material significantly impacts inductance. A core with higher permeability enhances inductance by concentrating the magnetic field and allowing it to penetrate the core more effectively.

5. Core Geometry: The shape and geometry of the core can affect inductance. Different core shapes, such as toroidal (doughnut-shaped) or E-I cores, can alter the inductance characteristics of an inductor.

6. Coil Self-Capacitance: The presence of parasitic capacitance between the turns of wire in the coil can influence inductance, especially at high frequencies. This capacitance can interact with the inductance, affecting the overall impedance and behavior of the inductor.

7. Wire Material and Gauge: The type of wire used in the coil and its gauge (thickness) can influence inductance. Different materials and wire sizes have different electrical and magnetic properties that affect inductance.

8. Number of Layers and Winding Style: The way the wire is wound in layers and the winding style can also impact inductance. For instance, changing the winding style from single-layer to multi-layer can alter inductance.

9. Frequency: In some cases, inductance may vary with frequency due to factors like skin effect, proximity effect, and eddy currents. These effects become more pronounced at high frequencies and can influence the effective inductance of the component.

It's important to note that in practical inductor design, these physical parameters are carefully considered and adjusted to achieve the desired inductance value for a particular application. Additionally, manufacturers often provide datasheets specifying inductance values at different operating conditions and frequencies to help engineers choose the right inductor for their needs.